Not particularly more than others. "Subtract broad group of foods" is the bit that sets off the "fad diet" flag for me. The weekly cheat day is psychologically brilliant for helping compliance and I expect it to show up in other fad diets in future.

Ferriss is pretty gung-ho about the slow-carb diet (and says he lives on it himself and has done for the past seven years), and claims it works for everyone who's compliant, so I expect studies with a suitably sceptical eye will follow in due course if it gains any popularity.